Method for producing an electrical contact for an optoelectronic semiconductor chip

Abstract

A method for producing an electrical contact of an optoelectronic semiconductor chip ( 1 ), comprising providing a mirror layer ( 2 ), comprised of a metal or metal alloy, over the semiconductor chip; providing a protective layer ( 3 ) over said mirror layer; providing a layer sequence of a barrier layer and a coupling layer ( 5 ) over said protective layer; and providing a solder layer ( 8 ) over said layer sequence.

1. A method for producing an electrical contact of an optoelectronic semiconductor chip, the method comprising:
 providing a mirror layer comprised of a metal or metal alloy, over the semiconductor chip; 
 providing a protective layer over said mirror layer; 
 providing a layer sequence of a barrier layer and a coupling layer over said protective layer; and 
 providing a solder layer over said layer sequence, 
 wherein the electrical contact is patterned by a lift-off technique in which a mask layer having an undercut is applied to the semiconductor chip, the mirror layer is vapor-deposited in a directed manner, and the barrier layer is applied by a multiple directions covering coating method so that the barrier layer completely covers layers underneath. 
 
   
   
     2. The method for producing an electrical contact as claimed in  claim 1 , further comprising applying a layer of an electrically conductive material having a thickness between 0.1 and 0.5 nm to the semiconductor chip before the application of the mirror layer to improve the adhesion of the mirror layer. 
   
   
     3. The method for producing an electrical contact as claimed in  claim 2 , wherein the semiconductor chip has a surface formed of a nitride compound semiconductor material, the mirror layer contains Al or Ag, and the layer of electrically conductive material contains Pt, Pd or Ni. 
   
   
     4. The method for producing an electrical contact as claimed in  claim 1 , wherein said mirror layer is comprised of silver, and the method further comprises annealing the semiconductor chip at approximately 300° C. to improve adhesion of said mirror layer to the semiconductor chip. 
   
   
     5. The method for producing an electrical contact as claimed in  claim 1 , wherein providing said layer sequence comprises providing said barrier layer over said protective layer, and providing said coupling layer over said barrier layer. 
   
   
     6. The method for producing an electrical contact as claimed in  claim 1 , wherein the semiconductor chip has a surface formed of a nitride compound semiconductor material. 
   
   
     7. The method for producing an electrical contact as claimed in  claim 1 , wherein the mirror layer contains Al. 
   
   
     8. The method for producing an electrical contact as claimed in  claim 1 , wherein the mirror layer contains Ag. 
   
   
     9. The method for producing an electrical contact as claimed in  claim 2 , wherein the layer of electrically conductive material contains Pt, Pd or Ni. 
   
   
     10. The method for producing an electrical contact as claimed in  claim 2 , wherein the layer of electrically conductive material contains Pt. 
   
   
     11. The method for producing an electrical contact as claimed in  claim 2 , wherein the layer of electrically conductive material contains Pd. 
   
   
     12. The method for producing an electrical contact as claimed in  claim 2 , wherein the layer of electrically conductive material contains Ni. 
   
   
     13. The method for producing an electrical contact as claimed in  claim 1 , wherein said mirror layer is comprised of silver. 
   
   
     14. The method for producing an electrical contact as claimed in  claim 1 , further comprising annealing the semiconductor chip at approximately 300° C.